title: QIGLF, a novel angiotensin I-converting enzyme-inhibitory peptide from egg white protein.
abstract: BACKGROUND
  Novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from egg white protein can be rapidly screened by liquid chromatography/tandem mass spectrometry (LC/MS/MS). In this study, several peptides with higher ACE-inhibitory activity were prepared from egg white protein by enzymatic hydrolysis with Alcalase, purified with Sephadex G25, identified by LC/MS/MS and their structure determined by circular dichroism (CD) spectroscopy.
  
  
  RESULTS
  Peptide sequences DHPFLF, HAEIN and QIGLF that showed ACE-inhibitory activity were investigated further for their stability in gastrointestinal solution and for changes in their secondary structure in solution mixtures. QIGLF exhibited the highest activity (IC(50)=75 µmol L(-1)) and was resistant to digestion by proteases of the gastrointestinal tract. The CD spectrum of QIGLF showed the presence of the α-helix conformation.
  
  
  CONCLUSIONS
  Three peptides were identified by LC/MS/MS and synthesised by Fmoc solid phase synthesis. Of the three, only the peptide sequence QIGLF was a potential ACE inhibitor, with an IC(50) value of 75 µmol L(-1) . Moreover, QIGLF showed low gastrointestinal enzyme susceptibility and contained a relatively high amount of α-helix.
authors.affiliation: Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, China.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Yu
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Zhao
authors.forename: Jingbo
authors.initials: J
authors.lastname: Liu
authors.forename: Jing
authors.initials: J
authors.lastname: Lu
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D002645:Chickens; D004063:Digestion; D004355:Drug Stability; D004527:Egg Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D041981:Gastrointestinal Tract; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D010447:Peptide Hydrolases / Q000378:metabolism; D011487:Protein Conformation
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D004527:Egg Proteins; D010446:Peptide Fragments; C561682:glutaminyl-isoleucyl-glycyl-leucyl-phenylalanine; D010447:Peptide Hydrolases